会展最大的功能是（）。A.促进交易 B.传播形象 C.建立与各方面的合作关系 D.宣

已知方程x²+y²+kx+2y+k²=0所表示的圆有最大的面积，则直线y=（k-1）x+2的倾斜角α=______．

用适当的介词填空。

1.—Where was your sister born? —She was born ______ Shanghai.

2. The date ______ her grandmother's birthday is July 18.

3. Look! There are a lot of birds ______ that tree.

4. How many months are there ______ a year?

5. Kate's kite is ______ that tree. She can't get it down.

6. We have a sports meeting every year ______ school.

7. The shoes ______ the bed are my parents'.

8. Welcome ______ our sports club.

9. Can you take the notebook ______ the reading room for Tom?

10. Her brother was born ______ December 24.

髓的主要作用是（）。

A.支持

B.营养

C.输导

D.细胞分裂

素有“煤铁之乡”之称的省份是哪一省？

在瓷横担线路上禁止（），在转动横担的线路上（）前应将横担固定。